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Would this idea to prolong battery life work? (NOT perpetual motion, just extended life!) Answered

A few days ago, I designed a self-charging battery system using a dc motor attached to a rechargeable battery pack that turns a generator via gears, similar to how a car battery works, converting kinetic energy from the motor to electrical energy with the generator and looping back to the battery. I've modified the idea to reduce friction as much as I can so that the motor and generator are directly attached now, keeping energy from being lost to friction between gears. Here's a crappy diagram:

I know that 100% efficiency is impossible, I'm not trying to get all the energy back, and I'm not trying to create energy. I'm trying to loop the energy that isn't lost to friction and other factors back to the battery, hypothetically charging the battery up a little to somewhat extend the life. I realize that it will eventually go dead no matter what I do due to the laws of thermodynamics.

What I want to know if this would increase the battery life enough to be worth incorporating in a design.

(I know the motors should be attached to the battery by two different ends but its actually supposed to be a rechargeable battery pack so one motor is attached to input in to charge the battery and the other is output so the battery powers it. Plus if I tried to draw the wires like that it would've taken forever.)

10 Replies

It would work for a time, but then get slower and slower...and the battery would die.

Laws of thermodynamics aside (or rephrased at least) - you CANNOT get something for nothing. Energy, like matter is 'stuff' that you can't just magic out of nowhere. It's measurable and has units. Likewise you can convert it from chemical in the battery to electrical potential in the wire, to mechanical in the motor (via magnetic), back to magnetic, then back to electrical...and technically back to electrical. Yes, you can do that - BUT - every conversion is less than 100% efficient, letting some of that energy go as heat (or other unusable waste) so you get slightly less in the wires as you had in the batteryslightly less still in the magnetic field as you had in the wiresless mechanicalless les...lesss.....none.

If your contraption worked, then why use the contraption, you could just leave the battery by itself and it would charge itself.

Here's the key. You use more power turning the motor that turns the generator, than you generate and put back into the battery. You are already behind and you haven't even considered the power you use actually doing something.

+1. It's only a net load on the battery, therefore it would reduce battery life. AT BEST, if you could get perfect efficiency, it would have no effect.... and perfect efficiency doesn't exist; trying to go cheap (using a motor rather than a proper generator) makes you even less efficient.

Basic thermodynamics:

1) You can't create heat (or other forms of energy).2) You can't move heat without losing some (perfect efficiency is impossible).3) A closed system becomes more disorderly over time (meaning everything levels out/flattens out -- until you get to quantum effects like superconductivity, anyway).

Or, in the easy-to-remember version:

1) You can't win.2) You can't break even.3) You can't get out of the game.

If your design violates these rules, either you're up for a nobel prize or you're "not even wrong." I leave it to you to guess which is more likely.

You wouldn't really be able to power anything with it since even though its being charged with the motor you would lose energy through the motors. Even if you lost no energy through the two motors, it would just end up being like a battery without any motors. Sorry if this was confusing.